Abstract:A sustainable society has been said to require knowledge of the limits placed by nature. Whatever one’s views on the know-ability and significance of such limits, science strives to improve our understanding of these limiting factors, of which water is recognized to be one of the most important. Despite the centrality of water, the water cycle is maddeningly difficulty to pin down with the level of detail that is desired for resolving issues about the fate of pollutants, nutrient cycling and the global carbon balance, etc. But there is hope lurking in the Swedish landscape. The simplicity of hydrology in many Fennoscandian till soils, combined with applications of the only true tracers of water (isotopes of the water molecule) provide a hydrological basis for breakthroughs in the biogeochemistry of critical earth support systems. This talk will explore some recent advances in understanding the role of the riparian zone for the “aquatic conduit” of terrestrial carbon, with linkages to the hydrological basis for water quality issues in general. The talk will finish with thoughts about where to go next with the power that a well-characterized hydrology can provide.